iamfrazzled wrote:

Leanmeamum Thanks so much for this sorry to be dim but why do you also need to see what the LCM of 2 is ? Also how on earth are dc supposed to know these tricks of the trade. Everytime I think we are getting somewhere with maths another of these things come along. GS stage 2 Exam is 8 days time now!

Sorry my mistake - I added 2 to the question.

Maths problem solving is quite tricky but the best way to overcome this is to practise as much as possible.

LCM or the Lowest Common Multiple is very easy to work out. The LCM means the smallest number which can be divided by all the numbers in a given list of numbers without leaving a remainder.

LCM can be calculated in 2 ways -

1) Foe eg. we need to find the LCM of 2, 6, 8 The child can list all the multiples of all the numbers

2 = 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 .....................

6 = 6, 12, 18, 24, 30, 36, .............

8 = 8, 16, 24, 32, .............

We can see that 24 is the first number which is common to all 3. There the LCM for 2, 6 and 8 is 24

2) The second method is as follows - This method is difficult to show without symbols but I'll try to explain it

we write all 3 numbers next to each other and start dividing them together. All numbers are divided by the same number and if they can't be divided they are divided by their own factors. We need to use prime numbers to divide them as bigger numbers can give a wrong answer

2, 6, 8 divided by 2 = 1, 3, 4 (I'm taking these numbers and dividing them again as you can see in the next line)

1, 3, 4 divided by 3 = 1, 1, 4

1, 1, 4 divided by 2 = 1, 1, 2

1, 1, 2 divided by 2 = 1, 1, 1

We can't divide them any further as all numbers have been reduced to 1

Then we take the numbers we used to divide the group and multiply them. So we take 2 X 3 X 2 X 2 = 24 to give us the LCM for 2, 6 and 8